A small Javascript function that extrapolates in-string code like Ruby does.

extrapolate.js

/*
  extrapolate.js
  ==============
  
  A small utility function that allows Ruby-like string extrapolation 
  via #{expr}. Relies on ES5's Array#forEach but is relatively easy 
  to convert not to use it. 
  
  ...that's it, folks!

*/
String.prototype.extrapolate = function() {
  var str = this;
  this.match(/#\{(.+?)\}/g).forEach(function(each) {
    str = str.replace(each, eval(each.slice(2, -1)));
  });
  return str.valueOf();
};